JPH06174628A - Method and device for measuring distribution of grain size of flowing solid granular substance - Google Patents

Abstract

PURPOSE: To obtain the distribution of particles contained in sample by disposing the sample to be measured between a light source and image capturing means, moving the sample, intermittently illuminating the sample in a pulse state, and processing the signal from the means. CONSTITUTION: A pulse laser source 1 is opposed a image capturing means to a television camera 3 synchronized with it, a measuring chamber 5 is provided therebetween, and liquid sample containing suspended particles flows therein. The beam from the source 1 projects the image of the particles in the chamber 5 to the camera 3 via an optical element through the chamber 5. The image is sent to a computer 9 via an image capturing system 7, the image is analyzed, the size of the particle is calculated, the distribution of the sizes of the particles is calculated, and degree distribution view and diagram are generated as required. An electronic control system 11 is controlled by the computer 9 to send a synchronizing signal to the source 1 and the camera 3.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method and apparatus for measuring the particle size distribution of flowing solid particulate matter by image analysis. More specifically, the present invention provides that the sample to be measured is arranged between a light source and a means for capturing an image, and a means for capturing an image of particles contained in the sample projected onto the capturing means, It also relates to a method in which the signal obtained from the capture means is processed to show the size distribution of the particles contained in the sample.

[0002]

2. Description of the Related Art A method of this kind is described in Italian Patent Application No. 6
9199A / 79 and Italian Patent Application No. 5904A / 81 relating to improvements of the method disclosed in that patent. In these known methods, the sample is substantially stationary with respect to the capture means, a continuous light source illuminates the sample, and an image of the particles of a sensor, for example an array of photoelectric transducers arranged side by side. Projected in rows. The signal thus obtained is processed and the particle size is determined by indirectly measuring a series of different parts of the particle.

Sometimes it is necessary to measure a flowing sample. For example, it may be necessary to obtain in real time data on the particle size distribution of the sample, which may vary with time. In such a case, a diffractive indirect measurement system has been conventionally used. This type of method requires a long measuring time to calculate the particle size distribution.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a method and apparatus capable of measuring particle size distribution by image analysis (ie, the direct method) even on a flowing sample.

[0005]

In order to achieve the above-mentioned object, according to the present invention, in a method of measuring the distribution of particle size by screen analysis, the sample to be measured is a light source and an image capturing means. Is arranged between the means for capturing the image of the particles contained in the sample, which is projected there, and the signal obtained from the capturing means is processed to show the size distribution of the particles contained in the sample. , The sample to be examined is moving, and-the sample is illuminated by pulses in a discontinuous manner.

The method according to the invention is generally characterized in that the sample to be examined is moving and that the illumination of the sample is discontinuous in the form of pulses. The pulse of light is
The duration is sufficiently short compared to the flow rate of the sample so that the capture means can observe a substantially fixed image. By capturing a series of images, it is possible to find a time-proportional distribution of the sample particle size while the sample is flowing through the measuring device. The claims show the best embodiments of the method according to the invention.

The device according to the invention comprises means for capturing an image of the particles contained in the sample and means for processing the signal captured by said capturing means. According to the invention, the device is characterized in that it comprises a pulsed light source and a measuring chamber arranged between said light source and the capturing means, which allows a continuous flow of sample.

[0008]

The best mode for carrying out the method according to the invention is set forth in the appended claims and will be described below with reference to the accompanying drawings, which show examples of the invention.

FIG. 1 is a block diagram of an apparatus according to the present invention. FIG. 2 is a vertical sectional view of the device. FIG. 3 is a cross-sectional view of the device taken along line III-III of FIG. Figure 4
3 is a very simple flow chart of the work performed by the device according to the invention. 5 and 6 are views showing the measurement chamber, FIG. 5 is a partial sectional view taken along line VV of FIG. 6, and FIG. 6 is a partial sectional view taken along line VI-VI of FIG. is there.

Briefly first with reference to FIG. 1, the device comprises a light source 1 arranged facing an image capturing means 3, said light source being in particular a pulsed laser light source. The capture means may be a television camera synchronized with a pulsed laser in the manner described below. A measurement chamber, generally designated by 5, is provided between the light source 1 and the capturing means, through which a liquid sample containing suspended particles flows. The light rays emitted from the light source 1 impinge on this chamber 5 (with transparent walls). The chamber 5 and the TV camera 3
An optical system placed between projects an image of the particles in the chamber 5 onto the television camera 3. The resulting image is sent through a known type of image paving system, generally designated 7, to a computer 9 where diffraction of the image and calculation of the size of the trapped particles are performed, based on which the particle The size distribution is calculated and, if necessary, a frequency distribution diagram or diagram is generated.

The computer 9 also controls an electronic control system 11, which controls the light source 1.
And a signal synchronized with the TV camera 3 is sent to the TV camera 3, and the TV camera 3 synchronizes with the pulse of the light coming from the light source 1 by this synchronizing signal. And (because the scanning signals of the television camera are synchronized), it becomes possible to capture an image of particles in the chamber 5 that are actually moving at a fixed speed in the chamber 5.

2 and 3 show the structural details of the device shown diagrammatically in FIG. More specifically, a light source 1, a measuring chamber 5 and a television camera 3 facing the light source 1 and on the opposite side of the measuring chamber 5 are shown. A microscope 13 is arranged between the measuring chamber 5 and the television camera 3 to form a magnifying optical element for the television camera 3 so that an image of very small particles can be captured. The optical element 13 has a front view, ie the distance between the sample and the objective lens, which is long enough to avoid interference with the wall of the measuring chamber 5. Furthermore, the optical element has a depth of field which is sufficient compared to the width of the chamber 5 and in this case approximately equal to the width.

A liquid sample containing suspended particles is placed in a reservoir 15 to dilute the sample if necessary. The reservoir is equipped with a magnetic stirrer 17, a device for the sample for recirculation and subsequent processing, and a measuring chamber 5.
It is connected to a three-way valve for cleaning. The sample is removed from the reservoir 15 using a pump, such as a pump drive. The sample pumped from the reservoir 15 is sent to the expansion tank 23, which is arranged above the measuring chamber 5 and connected to the chamber by a pipe 25. A discharge pipe 27 is also arranged in the measurement chamber 5.

The device is provided with a focusing means consisting of a slide 29, on which a television camera 3 and a microscope 13 supported by a support rod 31 are mounted, which are generally designated by 33. It is connected to a focusing system of known type. A detailed description of the focusing system will be omitted. The focusing system also includes a comparator 34 which is used to facilitate focusing when a chamber 5 replacement operation is performed. Finally, the device has a compartment 35 in which the electrical components are housed.

Image capture and analysis and measurement of particle size distribution will now be described with reference to the schematic diagram of FIG. The number K of images to be thinned is set in the computer 9. An initial pulse is then generated to synchronize the laser light source 1 and the television camera 3 and the corresponding image is captured by the system 7 and sent to the computer 9 to calculate the particle size. This calculation is performed using image analysis software known per se (eg,
You may use the software package sold by the Danish company Gate Data under the GIPS trade name). The data obtained by this calculation is stored, the counter N is advanced, the value of this counter is compared with the set value K, and further pulse generation, image generation are performed until the counter N exceeds the set value K. The process of acquisition, size calculation and storage is repeated. at this point,
The computer 9 proceeds to calculate a frequency distribution chart and other diagrams summarizing the particle size distribution determined by processing the captured K image. Using this computer 9, the calculated frequency distribution chart can be printed out or displayed on the display screen.

Through this measurement process, the drive pump
21 and the magnetic stirrer 17 continue to operate so that a sample containing suspended particles is taken from the reservoir 15 and circulated through the expansion pump 23 into the measuring chamber 5. The measurement chamber 5 is preferably formed in a modular structure so that the range of sampling amount can be easily changed. In this way, it is possible to measure a highly diluted sample, i.e. a sample with a low particle density (assuming there is a sufficient sampling volume and the optical element has a sufficiently large depth of field). . As a result, the amount of light incident on the television camera 3 is increased, and an image with high contrast, that is, an image with high image quality can be obtained.

5 and 6 are views showing a concrete example of the measuring chamber 5. The chamber is attached to the support portion 51 using the fixing knob 53. The chamber body consists of two flanges 55,57 with two central optical glass openings 59,61. These two flanges
It is seamed with screws 63 and a metal 65, for example made of baked steel, which serves as a spacer
It is arranged between the flanges. The metal plate 65 has two openings
It has a central elliptical opening 67 concentric with 59, 61. The space within the opening 67 bounded by the elliptical edges of the opening and the inner surface of the mouths 59, 61 is connected to the reservoir 15 by a first inlet pipe 69 and a second outlet pipe 71 for flow. Determine the volume of the chamber that was set. The two tubes 69 and 71 are inclined at an appropriate angle with respect to the horizontal in order to prevent the precipitation of particles in the chamber 5.

The depth of the measuring chamber can easily be changed by replacing the plate 65, without exchanging the other components of the chamber and without having to reconnect the tubes 69, 71. You can

It will be readily understood that the drawings are intended to illustrate embodiments of the invention and that the invention may vary in form and arrangement without departing from the scope and concept thereof.

[Brief description of drawings]

1 is a block diagram of an apparatus according to the present invention.

FIG. 2 is a vertical cross-sectional view of the device.

FIG. 3 is a cross-sectional view of the device taken along line III-III in FIG.

FIG. 4 is a very simple flow chart of the work performed by the device according to the invention.

5 is a partial cross-sectional view taken along the line VV of FIG.

6 is a partial cross-sectional view taken along line VI-VI of FIG.

[Explanation of symbols]

1 Laser 3 TV camera 5 Chamber 7 Image capture system 9 Computer 11 Electronic control system

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Carlo Castellini Italy. 50144, Firenze. Via J. B. Uri Niumero. 50

Claims (18)

[Claims] 1. A method of measuring a particle size distribution performed by screen analysis, wherein a sample to be measured is a light source and an image capturing means, and means for capturing an image of particles contained in the sample projected onto the sample. Disposed between the two, the signal obtained from the capture means is processed to show the size distribution of the particles contained in the sample, the sample to be examined is moving, and the illumination of the sample is A method that is performed discontinuously in pulses. 2. A) pulses are generated to synchronize the light source and the capture means; b) an image is captured; c) image data is transmitted to a computer to calculate particle size and store the data. , D) The steps of (a), (b), and (c) are repeated a predetermined number of times, and e) the particle size distribution of the sample width is calculated based on the stored data. The method according to 1. 3. The method according to claim 1, wherein the sample is irradiated with a pulsed laser light source. 4. The method according to claim 1, wherein the sample comprises a moving fluid medium containing suspended particles. 5. An apparatus for measuring particle size distribution performed by image analysis, comprising a light source, image capturing means for capturing an image of particles contained in the sample projected by the light source, and No means for processing the signal captured by the capture means, the light source is a pulsed light source, a measurement chamber allowing continuous flow of sample is arranged between the light source and the capture means Equipment. 6. The apparatus according to claim 5, wherein the light source is a pulsed laser. 7. The apparatus according to claim 5, wherein the image capturing means is a television camera. 8. An apparatus according to any one of claims 5 to 7, comprising pulse generating means for synchronizing the light source and the capturing means. 9. Processing the image signal coming from said capture means,
9. An apparatus according to any one of claims 5 to 8 having a computer for sending a synchronization signal to the light source and the capture means. 10. The particle size of a sample to be inspected from the data obtained by processing the captured signal, wherein the computer performs a task of capturing and processing the image signal by a predetermined function. 10. The apparatus of claim 9 programmed to determine a distribution of. 11. An apparatus according to any one of claims 5 to 10 wherein the capture means is connected to focusing optics and, if required, magnifying optics. 12. The apparatus according to claim 11, wherein said optical element has a depth of field close to the depth of the measurement chamber along the direction of the light rays coming from said light source. 13. A plate shape having two flanges each having a transparent wall portion in the measurement chamber, and an opening arranged between the two flanges to define a sample holding container of the chamber. 13. A device according to any one of claims 5 to 12 having a spacer according to claim 5. 14. The apparatus according to claim 13, wherein the plate-shaped spacer is replaceable. 15. The device according to claim 12, wherein a tube for introducing and discharging a sample is connected to one of the two flanges. 16. A device according to claim 14, wherein the tube is inclined with respect to a plane defined by plate spacers. 17. The apparatus according to claim 5, wherein an expansion tank is arranged in front of the measurement chamber. 18. The apparatus according to claim 5, further comprising a reservoir in which the sample is diluted and constantly stirred.